Feathering-blade propeller



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FEATHERINGBLADE PROPELLER Filed Aug. 13, 1941 2 Sheets-Sheet 2 Inventor M'ilion D-Tfizn eon. 3) 4g I Patented May 19, 1942 mam UNHTED STATES PATENT QFFEQE 2,283,774 FEATHERING-BLADE PROPELLER Milton D. Thompson, Fairhaven, Mass. Application August is, 1941, Serial No. 406,595

4 Claims. 7 (Cl. 170-462) This invention relates, in general terms, to screw propellers, but deals more specifically with a propeller having the so-called feathering type blades which adapts it for use with auxiliary power plants on sailing vessels.

It is not my intention at this time to discuss the prior art further than to mention the fact that a patent on a device of the above character was granted me October 25, 1938, Numbered 2,134,157, the blades of which had but one working face, serving for both ahead and astern movements of the vessel. The grooves in the propeller hub by means of which the blades were axially rotated were dissimilar in contour, which permitted one blade to start rotating on its axis in advance of the other.

Furthermore, because they were single working face blades an axial rotation of approximately 180 degrees was required to bring the working face from ahead to astern position.

Due, however, to certain features, among which might be mentioned the cost of production and the requirement of extra fine workmanship on the more or less intricate groove structure, and notwithstanding the fact that the propeller on the whole is a very efficient one in actual service, I have decided that for general use a propeller of the feathering blade type can be produced which would fulfill all the requirements of a device of this kind, at less cost and simpler in structure.

My present invention is the outcome of this decision, and in this later conception I have a propeller each blade in which has two working faces, the one which handles the ahead movements of the vessel being the more efiicient.

The grooves in the propeller hub of my present invention are dissimilar to, much shorter and of less pitch angle than, those in my former device.

As a consequence the grooves are capable of more easily rotating the blades on their axes when change in direction of movement of the vessel is required.

The blades are interchangeable and of the outof-balance type, that is, a large preponderance of the blade surface is on the trailing side of their axes.

In the accompanying drawings illustrative of my invention, and made a part of this application, I have disclosed what, at this time, I consider a preferred embodiment of my invention; and in the drawings in which like reference characters indicate like parts throughout the various views:

Fig. 1 illustrates a left-hand pitch feathering blade propeller, the full lines showing the blades set for ahead movement of the vessel when the shaft is rotating as indicated by the arrow, the dotted line depiction of the blades showing them in feathering positions;

Fig. 2 is an end-0n view of one of the blades, or as would be viewed by rotating Fig. 1 ninety degrees;

Fig. 3 is a section on line 3-3, Fig. 1;

Fig. 4 is a fragmentary view of the propeller with one half of the split casing removed, showingthe parts as they are arranged in Fig. 1, for "ahead movement of the vessel;

Fig. 5 is like Fig. 4 except that the parts are arranged for astern movement of the vessel;

Fig. 6 is like Fig. 4 except that the blades have been moved into their feathering positions; and

Fig. '7 shows the two (for a two-blade propeller) similar grooves on the propeller shaft hub developed on a plane surface to more clearly show their contours.

Referringto Figs. 1 and 4 of the drawings, B

represents the blade of a two-blade,-left-hand pitch propeller, of the feathering-blade type. It is obvious that a right-hand pitch blade would have equal application, and that more than two blades might be incorporated in the structure were certain changes in mechanical structure made.

I is the propeller shaft, secured to which by a key 2 and a nut 3 is a propeller-shaft hub member having outer end straight journal portions 4 and an intermediate portion 4a. of frusto-spherical shape, as shown in Fig. 5.

In the portion 4a are two similarly contoured grooves .5, placed diametrically opposite each other. Should there be more than two blades in the propeller a corresponding number of grooves would, of course, be provided.

In Fig. '7 these similarly contoured grooves are shown as they would appear on a plane surface developed from the frusto-spherical propellershaft hub on which they are cut.

Enclosing the propeller-shaft hub is a split, two-part casing 1, the end portions 8, 8 of which serve as bearings for the ends 4, 4, respectively, of the shaft hub. The shaft hubmay rotate a limited amount in the casing bearings the outside of which are screw threaded at 9, 9, to receive collars I0, I!) for clamping the two sections of the casing together.

On opposite sides of the assembled casing 1 is an annular flange H, and on the hub l2 of each blade B is cut a circumferential groove l3 within which the flange I l is disposed and around which the hub l2 of each blade has limited rotation.

The outer faces of the flanges ll converge slightly toward the aft end of the propeller, producing a corresponding aftward rake to the propeller blades.

On the inner face of the hub of each of the blades B is a pintle l4 adapted to engage the adjacent groove 5 in the propeller-shaft hub portion 40.. In the three views shown in Figs, 4, 5 and 6, the pintle on but one of the blades is visible, that on the other blade being concealed by the shaft hub.

In Figs. 1 and 4 the blades are set for ahead movement of the vessel when the shaft is revolving as indicated by the arrow 40, and a lefthand blade is being employed. The pintle I4 is now disposed in groove 5 in the position X, Fig. '7.

Assume that the blades are to be brought into their feathering positions. This would require that the pintles l4 move to positions Z in the grooves 5, the direction of rotation of the propeller shaft being changed to permit of this.

But the only condition under which the blades will remain in their feathering positions is when the propeller shaft is idle and the vessel is being driven forwardly by its sails. So by simply shutting off the motor power drive the impact of the water on the trailing portions Ba of the blades will cause them to swing into more or less centralized positions, as illustrated in Fig, 6, the preponderance of blade surface aft of their axial lines, together with the forward movement of the vessel proceeding under sail propulsion will hold the blades thus disposed, automatically positioned in their centralized locations in which they cause very little drag or resistance to the progress of the vessel.

Should it become necessary to check the forward movement of the vessel, or to drive it sternward, the shaft is rotated in a direction as indicated by arrow 50.

The pintle I4 will now move to position Y, Fig. 7, the parts being arranged as shown in Fig. 5.

It will be observed by reference to Fig. 7 that the pintle positions X and Y align transversely of the shaft hub 4, on line L, the point X representing, relatively, the starting position of the blade on the ahead movement of the vessel, and the point Y the same for astern movement thereof, the propeller shaft rotating in opposite directions, respectively.

In ahead movements of the vessel the cutting or entering edge of the blade is El), whereas on astern movements it is Bc.

To limit the axial rotation of the blade a lug 60 is made on the periphery of the blade hub 12 which engages a stop element on the casing 1. For manufacturing convenience there are two of the stop elements on each half of the casing, thus providing for right-hand blades as well as left-hand ones.

Spanner wrench holes I 0a are made in each of the collars Ill for tightening the latter on the casing parts.

In my former patented propeller the single working face of the blade, serving in going ahead and backing movements of the vessel, made it a very efficient propelling element, generally.

But I consider that to more than offset its efiiciency in astern movements I have incorporated in my present invention advantages which will commend them to those in marine pursuits.

The design of the groove in my present propeller is very simple and effective. With the,

pintle in position Y, and rotating the shaft to bring it over into position X, the trailing portion of the blade encounters the force of the water and requires considerable pressure on the pintle to effect its turning, and this part of the whole movement from Y to X is accomplished mechanically, or in other words, by the propeller shaft hub itself.

But to overcome excessive pressure I make the groove between positions Y and Z longer and of less pitch angle so that the power required to swing the blade around into feathering position is much less than would otherwise be the case. But once in feathering position the blade, by the action of the impacting water, will complete the swinging movement with practically no assistance from the shaft hub as the pintle moves into the short arm of the groove structure, between Z and X.

Contrawise, when the pintle is in position X, with the motor power driving the vessel forwardly, upon releasing the power strain on the shaft hub which keeps the pintle in the position X, the blade will automatically swing into position Z, due to the impaction of the water on the portion Ba of the blade.

The portion of the groove between positions Y and Z is a true helix, and this accounts largely for the easy and smooth movement of the pintle from one to the other of these positions.

What I laim is:

1. A feathering-blade propeller comprising a propeller shaft hub member having a longitudinal bore therethrough, a split casing enclosing and rotatable on said shaft hub, an axially rotatable unbalanced, two-working-face propeller blade mounted on the side of said casing, a pintle on the hub of said propeller blade, and a twobranch groove on the periphery of said shaft hub member with which said pintle has engagement, said groove beginning and ending at -points in the same plane, transversely of said shaft hub member, one of said branches being relatively long and of true helix form and the other shorter and of slightly arcuate form, the propeller blade being similarly disposed with reference to said casing whether set for ahead or astern propulsion of the vessel, and brought from one position to the other in response to one continuous rotary movement of said propeller shaft.

2. A feathering-blade propeller mechanism comprising in combination with a propeller shaft, a propeller shaft hub member, secured on said propeller shaft, a split casing within which said shaft hub member has limited rotation, a doubleworking-face propeller blade mounted for axial rotation on the side of said casing, a pintle eccentrically positioned and integral with the hub of said propeller blade, a two-branch groove of helical and arcuate contour, respectively, with which said pintle has engagement, cut on the periphery of said propeller shaft hub member, said pintle in moving from one end to the other of the said two-branch groove causing said propeller blade to axially rotate to its feathering position and to then directly return, by a reverse-direction axial movement, to its original position, all occurring during one continuous rotary movement of said shaft hub member in said casing, stop means to limit the axial rotation of said propeller blade, and means to mutually secure the two portions of said casing.

3. A feathering-blade propeller mechanism comprising a propeller shaft hub member having a longitudinal bore therethrough, said hub member embodying straight end portions constituting journals, and an intermediate frusto-spherical portion, two similarly contoured grooves cut in the periphery of the frusto-spherical portion of said shaft hub member, each of said grooves comprising two branches, one branch being cut on the lines of a true helix and of comparatively fine pitch, this groove merging into another of coarser pitch and arcuate form, the ends of both branches of the groove lying in the same plane a propeller shaft hub secured to said propeller shaft, a split casing enclosingsaid shaft hub, and rotatable thereover within predetermined limits, an opening in the side of said casing surrounded by an annular flange, a propeller blade having two working faces, a peripheral groove in the hub of said propeller blade adapted to receive said annular flange and permit of limited rotation of said blade on its axis, a pintle on the hub of said blade, and a two-branch groove on the face of said propeller shaft hub in which said pintle operates, one of said branches being cut on a true helix of comparatively fine and predetermined pitch and merging into the other branch of much coarser pitch and of slightly arcuate form, the ends of the two branches being disposed in a plane normal to the axis of said propeller shaft, to the end that said propeller blade assumes the same position, relative to said casing, whether in ahead or astern propulsion.

MILTON D. THOMPSON. 

